For years, I've been tinkering with my HSS Strat to turn it into a universal instrument. After trying out many single coils, the Fender Noiseless N4 proved to be the best fit for me.
I installed several humbuckers on the bridge: Burstbucker 1, 2, and 61, Suhr SSV, DiMarzio 223 paf, DP190F, Gibson 490T with various magnets, Duncan Trembucker 59, TB-4, TB-5, and TB-14. There may be some missing from this list.
I settled on the Tonerider Alnico 4 Classic, the cheapest one! It doesn't drown out the single coils, has an open sound, and no frequency range is particularly emphasized. It has powerful, clear bass. It can sound like a PAF, and metal works too.
This was a very pleasant surprise and will stay in.